Illuminating apparatus



July 6,1926.. 4 l 1,591,211

. J. W. BRENKERT ET AL ILLUMINATING 'APPARATUS Fled'Feb. 15, 1926 A' Panarea July-6, 1926.

Josera w, Banirimnr Nn n r, or HIGHLAND '1f-anx, Ironman muma'rme Arrnnnr'us.

application ma February 1s, v192s. serial mi. ss,s71.

This invention relates to illuminating apparatus and has `special reference to that' class of light rojecting devices wherein a source of light 1s reflected to a lens for light 5 rojection va ing from a beam to a flood `spersion, an such apparatus is extensively used in theaters to provide a variety of sta e llighting effects, for instance from a smal spot light to a complete full illumination ofthe stage. .Invthis type of, apparatus and indeed in any type of illuminating appara-tus wherein .a source of light is re ected\tov a lens, there is a light.- aberration which'decreases the intensity of the light to be provjected. It is easy enough to inter ose a shutter or diaphragm'having a sma opening to produce a vsmall beam, 4but when a beam is projected a considerable distance there is not suicient intensity of light to provide desired llluminationat a' distance. Placing a shutter ina luminous cone reduces the cross section ofthe vcone vand cuts 'oi' margmal reiectedrays with the result that the 'intensity of the li 'ht source is materially s reduced in the projected beam' resulting' Y source of electrlcal energy.

from theapertured shutter.

Again in such illuminating apparatus it practically impossiblefto change lenses for A is di erent kinds o light rojection so the lens is ordinarily adjuste relative to the,`

source of light so that for beam projection the foci. is between the --reector and the lens; infront of the lens for flood projection, l

f and at thelens for projection intermediate A:i5 that of loodingand spotting;

instances there are stray lig t rays emitted from the luminous cone and these stra light rays reduce the intensit `of the Are acted g' ra s emanating from the ens.

4o r, il'o leliminate fthe. light aberrationl re-v ferred to above, increase the intensity of the light projection, facilitate operations inconnection. with illumlnatm apparatus, and

rovide a wider range o illumination un` '45 er more perfect conditionsfor a spotting or iooding' light projection are the main purposes of our invention which will be better `understood when the construction of the ap.

'cludes certain vstructures that ma holderior carbo'ns adapted to In au these- AOr, Spot paratus is described by aid of the drawing,

wherein v Figure 1 is a longitudinal sectional view of the illuminating apparatus; Fig. 2 -is a cross sectional View of.l the same, and l Figs. 3 to 6 inclusive are diagrammatic views of light projection.

The illuminatingapparatus necessarily inbe considered of a conventional form an these are a housing 1 ordinarily trunnioned, as vat2, in a yoke or support 3 that ma be rotatably supported for swinging the ousin froml sideto side while it may be tilted in. t e yoke.

or fork and by such universal movement serving a large area for illuminating pmposes. In the rear end of. the housing 1 is ordinarilya stationary -reflector -or mirror 4' of the parabolic or convexo concavel type with' an adjustable source of light 5 in .front ofthe reflector and as an example ofsuch source of light we. have shown a carbon reduce anv a suitable electrical arc when in circuit wit In the forward part -of -the housin' is ordinarily acondenser lens 6 and in; gs. 3 to 6 inclusive we show variouspositions of this lensrelative to a luminous cone7 formed: b light raysreected from the reflector4. I eosition ofthe lens lshown in Fig. 3 afor a iiood or wide dispersion 'of l1 ht' rays, and'with the lens Vmoved v outw'ar y from. the foci of the luminous cone a beam hsglht projection is obtaine dwhile in Fig. 4is own one of many light projectionsy between the maximum and' approximate'- illustrated Ain Figs-3 and 5 re- Spectiv'ely. Ad'ustment Aoth'elens 6 may/ be-accom lished in'various ways, but since we inten -to translate the linear movement, 00

setsof .bearings 9 for parallel stationary rodsv 95 y l 10. Slidableon theserods are the bearings- 11 of 'a platform 12 and mounted on said platform is a holder 13 for the lens 6.

On the platform 12, at a predetermined distance behind the lens 6, is a support 14 fora conventional form of iris diaphragm shutter 15 including a multiplicity of plates or aperture members 16 which may be adjusted to provide apertures ofvarious sizes when an osclllatory movement 1s imparted to a shutter actuating member 17 projecting from the side of the shutter housin The shutter actuating member 17 is. provi ed with a sector or arcuated rack 18 meshing with a pinion 19 rotatable in a bearingf20, carried by a pinion cage 22. Slidable in the upright 21 is a vertically disposed rack 23 meshing with the pinion 19 and with a pinion 24 in the cage 22. The pinion 24 is slidable on av spirally grooved guide rod 25 mounted in a support 26, carried -by the bottom wall 8 of the housing l. The pinion 24 has a pin or stud 27 extending into the groove 28 of the guide rod 25, said guide rod constituting a spiral member by which rotation may be imparted to the pinion 24 when shifted longitudinally of the guide rod by movement of the platform relative to said guide rod. For moving the platform 12A there isa longitudinally disposed rack 30 supported by hangers 31 from the platform 12. Meshing with the rack 30 is a pinion 32 mounted on a shaft 33, journaled in bearings 34, carrie-d by the bottom wall 8 of the housing 1. On the shaft 33 is a hand wheel 35 by which it may be conveniently rotated to reciprocate the platform 12 and cause such motion to be translated for an oscillatory movement of the shutter actuatin member 17. The

translating mechanism is designed s o that rear side of the shutter are practically wasted or produce a light aberration which is not desirable in connection with any` form of light projecting machine. Not only is there a light aberration but a reduction in the intensity of the reflected light which results in a weak beamv possessing very little illumina-ting value at a distance. To still obtain a desired spot li ht or beam projection without decreasing t e intensity of the reflected rays and without causing stray light rays to `interfere with such light intensity as we obtain, we have provided the adjustable shutter and arranged it soas to ybe automatically `adusted in accordance with the position of t e lens 6 relative to the reflector 4. This is best brought out in Figs. /3 to 5 inclusive showing different positions of the lens 6 relative to the reflector 4 and in each instance the diaphragm shutter provides an aperture approximately the cross section of a luminous cone. The shutter Vdoes not extend into the luminous cone nor is it spaced therefrom but provides a positive barrier for those rays which come from the outer yportion of the luminous cone and under ordinary circumstances proceed in such .divergent directions as t0 render it practically possible to light up, though unequally, surrounding spaces, thus detracting fromthe value of the luminous cone for` light projecting purposes. We believe We are the first to provide a focusing device' including a lens and shutter and wherein the shutter is automatically adjusted relative 'to a luminous cone during adjustment of the.l

lens relative to a reflector. Obviously there are various types of shutters' that m1 ht be employed and probably a different kind of translating mechanism, therefore we do not care to confine our mvention to any detalls of construction other than mentioned in. the' appended claims.

`What We claim is:-

1. In an illuminating a paratus wherein a lens and an adjustable s utter have a constant relation and are adapted to be bodily shifted relative to a luminous cone to re ulate the projection Y of light adjusta le means adapted for bodily shifting said lens' and shutter, and means operated from said adjustable means adapted to' adjust said shutter relative to said luminous cone.

2. An illuminating apparatus as called for in claim 1, wherein said shutter is of the iris dlaphragmtype adapted to provide a light emitting opening corresponding to a cross section of the luminous cone.

3. An illuminating a paratus as called for in claim '1, wherein sai shutter is of the iris diaphragm typ? and linear movement of sai lens and s utter asa unit is translated to oscillatory movement for shutter parts alone. i

4. In an illuminating apparatus, wherein a source of llight is reflected to' a lens for. light projection varying from a beam to a flood dispersion, and wherein the reflected .light is interruptedl to provide a ,ath of light projection :,-,a shutter adapte to interrupt the reflected light,.said shutter bein adjustable, and means ladapted to bod-ily an simultaneously move said lens and shutter relative to said source of light and adjust 4said shutter proportionally to the movement' of sa1d lens and shutter so that the intenity of thewreflected light is confined to the ens. 5. In an illuminating apparatus, a sourc of reflected li ht, a focusing device including an adjusta le shutter, and means adapted to simultaneously move said focusin device-relative to Vsaid source of reected 'ght 5 and adjust said shutter. n 6.' An illuminating apparatus as called for in claim 5, wherein said shutter is'of the iris diaphragm type.

7. An illuminating apparatus,A as 'oalled l Y for in claim 5, wherein said focusing device 10 and said shutter have aconstant propor tional movement lllinwhich anyI aberration of light rays is c o ed to the source of releoted light. A Intestimony whereofv weA ax our signa` 1.6 tures. x

, y KARL BRENKERT.

JOSEPH W. BRENKERT. 

